Semiconductor fabrication continues to strive to make individual electronic components smaller and smaller, resulting in ever denser integrated circuitry. One type of integrated circuitry comprises memory circuitry where information is stored in the form of binary data. Memory circuitry can be characterized by whether the data is volatile or non-volatile. Generally, volatile memory circuitry loses stored data when power is interrupted, while non-volatile memory circuitry retains stored data even during power interruption.
Some non-volatile memory devices utilize a material whose resistance can be controllably modified into two or more states of different resistance, thus enabling the devices to comprise settable memory. Exemplary particular types of memory devices which utilize such resistance variable material are programmable conductive random access memory and phase change random access memory. Phase change random access memory comprises a fast ion conductor or resistance variable material, typically a chalcogenide material having metal ions therein, which is disposed between two conductive electrodes. By way of example only, such are disclosed in U.S. Pat. Nos. 5,761,115; 5,896,312; 5,914,893 and 6,084,796 to Kozicki et al. Resistance variable materials are capable of assuming high resistance “off” and low resistance “on” states in response to a stimulus for a binary memory, and multiple generally stable states in response to a stimulus for a higher order memory. The resultant memory element is non-volatile in that it will maintain the integrity of the information stored by the memory cell without the need for periodic refresh signals, and the data integrity of the information stored by these memory cells is not lost when power is removed from the device.
As new variable resistance chalcogenide materials for memory devices are developed, new techniques need to be developed to be able to pattern such materials into desired shapes and configurations for memory cells.
While the invention was motivated in addressing the above identified issues, it is in no way so limited. The invention is only limited by the accompanying claims as literally worded, without interpretative or other limiting reference to the specification, and in accordance with the doctrine of equivalents.